Folding chair mechanism



Oct. 19, 1954 e. e. HICKOK FOLDING CHAIR MECHANISM 2 Sheets-Sheet 1 Filed March 14, 11952 /n ven for Glenn G. Hickok Oct. 19, 1954 cs. (-5. HICKOK 2,692,01 l

FOLDING CHAIR MECHANISM Filed March 14, 1952 2 Sheets-Sheet 2 /n ven for G/enn G. Hickok Afforney Patented Oct. 19, 1954 UNITED STATES ATENT OFFICE FOLDING CHAIR MECHANISM Glenn G. Hickok, Ionia, Mich.

Application March 14, 1952, Serial No. 276,583

3 Claims. 1

The present invention provides an improvement in a folding chair mechanism described and claimed in the patent to Glenn B. Morse, Number 2.596.424, assigned to the assignee of the present application. Experience with the mechanism discussed in the application above referred to established that certain relatively abnormal forces could be applied to the chair in certain positions which would render it unstable. While these forces did not result from the usual use of the chair, they did exist when a person stood. on the chair near the rear of the seat, as when using the chair in place of a ladder. It is of course highly desirable that a chair remain stable under all conditions, regardless of the normality of the use to which it is put. It is also desirable that a chair be capable of manufacture with the component parts of such convenient size as to minimize the material involved. The condition of instability referred to above has been found to occur in chairs constructed according to the conventional proportions which seem to be best suited for this type of article with regard to convenience of manufacture and economy of material. While it is possible to design a chair pursuant to the application above referred to in which the stability condition either does not exist or is not of sufilcient magnitude to be important, it is clearly preferable that the mechanism be modified so that the instability conditions are eliminated without the necessity of resorting to uneconomical proportions of the various components. The present invention provides the desired improvement in the mechanism referred to above, and establishes complete stability of the chair regardless of the position on the seat where load is applied. This improvement is achieved with but a variation in the formation of the components and conserves all of the various advantages of the mechanism as described in the above-identified application.

A detailed discussion of the nature of the tendency toward instability that is dealt with. by the present invention, and the various mechanical features, will be discussed by reference to the accompanying drawings. In these drawings:

Figure 1 presents a perspective view of a chair constructed according to the present invention, with the chair in the erected position.

Figure 2 shows a side elevation of the chair shown in Figure l, with the chair in the folded position.

Figure 3 is a side elevation of the chair shown in Figure 1.

Figure 4 is a section taken through the front and rear leg assemblies and indicating the mechanical details involved in the present invention, with the chair in the erected position.

Figure 5 is a side elevation of the chair indicated in the previous figures, with the mechanism beginning to move toward the folded position.

Figure 6 presents a section similar to that of Figure 4, with the mechanism in the condition shown in Figure 5.

Figure '7 shows a section taken on the plane 7-7 of Figure 4.

Figure 8 is a section taken on the plane 8-8 of Figure 4.

Figure 9 is a section taken on the plane 9-9 of Figure 6.

Referring to Figure 1 of the drawings, the chair illustrated includes the front legs I!) and H, the rear legs !2 and I3, a seat M, and a back [5. A tie rod It connects the front legs, and a similar rod l! connects the rear legs near the lower extremities as shown. Suitable rubber feet I8, 19, 2d, and 2! are provided at the lower ends of the legs as shown, according to conventional practice.

Referring to Figure 4, the front and rear legs l0 and 52 are shown pivoted to the seat [4 on the cross rods 22 and 23, respectively. Preferably, the construction shown in Figure 4 is the same on both sides of the chair. The rear leg I2 is provided with a projection 24 formed by a protruding portion of a reinforcing plate 25 secured within the rear leg as shown. The projection 24 slides along the front leg Iii Within the confines of the slot 26 during the folding and erecting operations, as discussed in the application above referred to. In the erected position of the chair, the projection 24 is limited in sliding movement by the upper end 2! of the slot 26. The angle at which the upper edge 28 of the projection 24 engages the end 2'! of the slot 26 establishes a tendency to urge the rear leg to the left as shown in Figure 4. This action is resisted by the shoulders 29 provided on the rear leg l2 which engage the rear surface 3d of the front leg ID. A bent ear 3! formed integrally with the projection 24 prevents complete withdrawal of the proiection from the front leg it so that the compo nents retain their assembled condition at all times. The assembly of the components in the relationship shown in Figure 4 in the first instance may be provided for in any one of a numher of fashions, as described in the above-identified application.

In the construction provided by the present invention, a U-shaped reinforcement 32 is provided within the front leg I0, with the legs of the U pointing generally to the right as shown in Figure 4. This member reinforces the front leg primarily in the area adjacent the cross rod 22, where the bending moment is the greatest. The reinforcement 32 has a function in addition to the mere strengthening of the front leg It, however. The upper end of this reinforcement provides a convenient point against whichthe rear leg may 'be locked with the chair in the erected position to give the stability characteristics outlined above.

Referring to Figure 3, the normal use of a chair may be considered as providing an-average force acting along the line of the arrow 33. However, it is very possible that a person may apply by the dotted arrow 34 by standing on the chair when using it in place of a ladder. When force is applied along the line of the dotted arrow 34., it will be recognized that such force is in large measure transmitted to the rear leg l2 through the cross rod 23, creating a counterclockwise movement about the point where the foot 20 rests on the floor. Such counterclockwise movement of the rear leg l2 is accompanied, due to the link connection between the front leg and the rear leg l2 affected by the seat M, by a counterclockwise movement of the front le in around-the point of contact of the foot IS with the floor. The seat l4 rotates in a clockwise direction. These movements are indicated by the arcuate arrows. The improvement provided by the present invention locks the folding chair mechanism. against the tendency to move in the direction described under the action of forces similar to those acting along the line of the dotted arrow 34.

The upper end of the reinforcement member 32 is provided with the ledge '35 formed inthe back of the U-shaped section. The ledge 35 provides a point against which-the hook 36 of the projection 24 engages, with the .chair in the erected position. The engagement of the hook 36 with the ledge '35 absolutely prevents any movement of the projection 24 downward along the front leg I0. In order to fold the chainthe rear leg 12 must first be moved substantially along its own axis in an amount suificient to disengage the hook 36 from the ledge 35. After this action has taken place, the projection 24 is free to move along the slot 26 during the foldin operation; It will be noted that forces applied to the chair along the dotted line 34 (refer to Figure 3) cause a tendency for the upper end of therear leg l2 to be forced into engagement with the front leg 18. Even though these forces arerelatively slight, they do suffice to maintain the engagement of the hook 36 with the ledge 35.- The hook isreadily disengaged, however, by the usual folding movement in which the chair is slightly lifted as by placing the hand under the forward portion of the seat [4. Such action has a natural tendency to disengage'the book 36 from the ledge 35, and to complete the folding movement, since weight is no longer applied to the lower portions of the legs of the chair.

Reference to Figures 5 and 6 will clarify the position of the various components at the early stages of the folding operation. The position of the bent ear 3| upon the projection 24 must of course be such that the rear leg 12 can move along its own axis a sufficient amount to disengage the hook'sfi' before the bent ear 3| contacts the rear wall of the frontleg I0.

Referring to Figure 7, details of construction are shown which facilitate the assembly of the front and rear legs, the seat, and the cross rods. The front leg [0 is provided With a hole 31 on its inner face of suitable diameter to receive the rod 22. In the initial stages of manufacture, the front leg Ill is provided with an aperture at the point 38 on its rear face opposite the rod 22. The reinforcement 32 is formed with a slot 39 on the inner face of sufficient breadth to receive the rod 22. After the components have been assembled in the relationship indicated, a plug-weldin operation is performed at the opening 38, serving to secure the end of the rod 22 in firm relationship with the leg l0. Similar construction is also provided at the rear leg l2, the rod 23 being received in a suitable aperture 49 on the inner surface of the rear leg, and also being embraced by a suitable slot 4! in the re nforcement 25. An aperture 42 is sealed by plug-welding in the same manner, serving to adequately secure the rod 23 with respect to the rear leg assembly.

The particular embodiments of the present invention which have been illustrated and described herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intention to claim the entire invention as disclosed therein, except as I am limited by the prior art.

I claim:

1. In a folding chair having. a seat, front legs pivoted to said seat at intermediate side portions thereof, said front legs having a hollow portion containing axial slots of less widththanthe inside width of said hollow portions disposed above said seat and opening rearwardly, rear legs pivoted to said seat at rearwardly disposed side portions, thereof, said rear legs having end portions rigid therewith and slideably received in said slots, retaining means carried by said end portions and disposed to engage the inside surface of said hollow portions adjacent said slots preventing complete Withdrawal thereof from said 'slots, and bearing surfaces adjacent the upper end of said rear legs disposed to engage 'a rearward surface of said front legs when said chair is erected, the improvement comprising, in combination: means forming a ledge disposed transversely to and Within at least one of the said front legs adjacent the normally uppermost end of said slot, and a hook member secured to the said end portion and adapted to engage said ledge to prevent downward movement of said end portion along said slot, said retaining means being disposed to establish sufficient freedom of axial movement of said rear legs in the erected position to engage and disengage said hook member from said ledge.

2. In a folding chair having a seat, front legs pivoted to said seat at intermediate side portions thereof, said front legs having a hollow portion containing axial slots of less width than the inside width of said hollow portions disposed above said seat and opening rearwardly, rear legs pivoted to said seat at rearwardly disposed side portions thereof, said rear legs having end portions rigid therewith and slideably received in said slots, retaining means carried by said end portions and disposed to engage the inside surface of said hollow portions adjacent said slots preventing complete withdrawal thereof from said slots, and bearing surfaces adjacent the upper end of said rear legs disposed to engage a rearward surface of said front legs when said chair is erected, the improvement comprising, in combination: a reinforcement disposed within at least one of said front legs opposite said slots; means forming a ledge on said reinforcement disposed transversely to and within said front leg adjacent the uppermost end of said slot, and a hook member secured to the said end portion and adapted to engage said ledge to prevent downward movement of said end portion along said slot, said retaining means being disposed to establish sufiicient freedom of axial movement of said rear legs in the erected position to engage and disengage said hook member from said ledges.

3. In a folding chair having a seat, front legs pivoted to said seat at intermediate side portions thereof, said front legs having a hollow portion containing axial slots of less width than the inside width of said hollow portion disposed above said seat and opening rearwardly, rear legs pivoted to said seat at rearwardly disposed side portions thereof, said rear legs having end portions rigid therewith and slideably received in said slots, retaining means carried by said end portions and disposed to engage the inside surface of said hollow portions adjacent said slots preventing complete withdrawal thereof from said slots, and bearing surfaces adjacent the upper end of said rear legs disposed to engage a rearward surface of said front legs when said chair is erected, the improvement comprising, in combination: a reinforcement member disposed within each of said front legs opposite said slots; and a hook member secured to the said end portion and adapted to engage the uppermost end of said reinforcements to prevent downward movement of said end portions along said slots, said retaining means being disposed to establish suflicient freedom of axial movement of said rear legs in the erected position to engage and disengage said hook members from said reinforcement.

Name Date Burnham May 29, 1951 Number 

